Hi,
I’m trying to change the frequency of the pump modulation, but I’m having trouble understanding some of the rationale behind the existing code, so I’d like to ask a few questions to clarify things before I start changing anything.
- The cycle time for the pump modulation is 1.05 times the cycle time for the experiment loop (OD measurement, stirring, etc.). However, I can’t make sense of the comment that explains why: “to avoid too much chaos when you come back around to pumping again”. My best guess for why this needs to be different is that, if it were the same, minor errors in timing would cause the pumping to drift in and out of phase with the main experiment loop over the course of days, whereas this intentional discrepancy causes the loops to move in and out of phase with one another every twenty minutes, thus leading to less systematic error. Is this reasoning correct? And if so, why not just run the pumping on the main experiment loop to ensure it stays in sync?
- The other part I’m struggling to understand is the part where the main loop pauses, after taking an OD measurement, for the duration of time that pump 2 would be on before it restarts the stirrer (here). The comment on that line references “regulateOD() above”, but the regulateOD() call above will only happen if running as a turbidostat (as I understand), while the pause in stirring happens regardless. If not running as a turbidostat, then there’s no reason to expect that pump 2 will actually be running during that pause, as the pump modulation and experiment loops will be drifting in and out of phase with one another.
Could you shed some light on any of this to help me understand what’s supposed to be going on here?
Thanks,
Christopher Brown
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